1. Field of the invention
The present invention generally relates to a heater control assembly mounted on an instrument panel of an automobile, for controlling the amount of blown air and the temperature to be set, and more particularly to a heater control assembly of a type in which it is connected by means of a cable to an air conditioner mounted in the automobile.
2. Description of the related art
According to a lever-type of the conventional heater control assembly, there is provided an operation lever arranged in front of an instrument panel, and a cable arranged behind the instrument panel and connected with the operation lever and the air conditioner. The cable is pulled and pushed by swinging the operation lever to control the air conditioner.
Further, according to a rotary-type of the conventional heater, there is provided a rotary knob arranged in front of an instrument panel, the same cable as described above and a transmission mechanism for converting the rotational movement of the rotary knob into an substantially linear movement of the cable to operate the air conditioner.
There is shown one of the rotary type of heater control assembly in U.S. Pat. No. 4,656,926. This conventional control assembly includes a rotary knob arranged in front of an instrument panel, a cable connected with an air conditioner, a lever connected with one end of the cable, and a transmission mechanism for transmitting a torque generated on the rotary knob to the lever. The transmission mechanism includes a first bevel gear rotatable together with the rotary knob and a second bevel gear engaging with the first bevel gear. The second bevel gear has a bottom surface provided with a curved cam groove in which a pin-like cam follower mounted on the lever is inserted.
With the above-described mechanism of the conventional assembly, when the rotary knob is rotated, the first and second bevel gears are rotated so that the lever may swing by the engagement of the cam groove and the pin-like cam follower to pull and push the cable in a linear direction, resulting in the control of the amount of blown air and the temperature to be obtained.
Meanwhile, in the above mechanism a play between the pin-like cam follower and the cam groove must be maintained in order to ensure a smooth movement of the cam groove and the pin-like cam follower. This means that the lever can swing within a slight angle even if the second bevel gear is stopped, so that the position of the cable is unstable, resulting in an undesirable accuracy of control of the air conditioner.